1. Field of the Invention
The invention relates to a method of manufacturing a turbomachine element and more particularly a subassembly comprising an external annular shell bearing a stator blade stage and an annular track of abradable material facing which the ends of the moving blades of a rotor stage move. The invention relates more particularly to a refinement making it possible to both simplify the formation of the track of abradable material and reduce the axial bulk and the weight of the element, overall.
2. Description of the Related Art
A turbomachine stage, such as, for example, a compression stage in a compressor, is arranged between an external annular shell and an internal annular shell, the shells being coaxial. The fixed stator blades extend between the two shells. The moving blades are driven rotation-wise inside the external annular shell so that the ends of these blades move facing a track of abradable material deposited on the internal surface of the external annular shell, upstream of the stator blades.
Hereinafter in the description the terms “upstream” and “downstream” are used to situate the structural elements relative to each other, taking as reference the direction of flow of the fluid inside the external annular shell.
FIG. 1 represents a known subassembly consisting of the external annular shell 11, the stator blades 13 and the track of abradable material 15. According to this arrangement, the external annular shell 11 has an internal rib 17 which separates an upstream portion 19 where the track of abradable material 15 is located from a downstream portion 21 where the stator blades 13 are fitted. Each blade has a platform 23 sunk into an annular groove 25 of the external annular shell. The rib 17 forms the upstream boundary of this groove. In the example described, the fixed blades 13 are joined to the external annular shell 11 by bolts 27. The final form of the external annular shell, on the internal side, is generally obtained by machining. The annular shell is generally metallic, for example made of aluminum, titanium or steel alloy. The abradable material is often a mixture of aluminum and resin deposited hot (plasma) or cold, or a “RTV” silicone.